Elucidating regulators required at the onset of reprogramming to pluripotency using heterokaryons and global bi-species RNAseq

 

1. Nuclear reprogramming reveals common principles and mechanisms that control cell fate.


Our lab pioneered the use of cell fusion to study nuclear reprogramming mechanisms in stable non-dividing heterokaryons and showed that the “terminally differentiated state” of a cell is not fixed and irreversible, but instead quite amenable to change. For example, muscle cells can induce muscle gene expression in human keratinocytes (ectoderm), hepatocytes (endoderm) and fibroblasts (mesoderm).

 

This cell fusion approach is now proving invaluable for elucidating the mechanisms that regulate nuclear reprogramming to pluripotency using global bi-species RNA-seq and loss of function (siRNA) approaches. We have identified several regulators and pathways crucial to initiating reprogramming to iPS. An additional focus is the mechanism of active DNA methylation, a bottleneck to reprogramming by cloning or iPS.

 

Heterokaryons formed by fusing an excess of mouse ES cells with human fibroblasts are advantageous for discovering novel regulators, as they exhibit rapid and efficient reprogramming enabling mechanistic studies not easily achieved in iPS. The common principles that underlie nuclear reprogramming by different approaches suggest that cell fate changes are fundamental to development and occurred throughout evolution.

 

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* Yamanaka and Blau, 2011, Cell (PDF)